National Repository of Grey Literature 67 records found  previous11 - 20nextend  jump to record: Search took 0.00 seconds. 
Predators and antipredator defence of Auchenorrhyncha (Hemiptera)
Zeman, Šimon ; Raška, Jan (advisor) ; Michalko, Radek (referee)
Auchenorrhyncha are one of the species-richest groups of hemimetabolous insects. They feed mostly on plant sap and play an important role in food webs of various ecosystems; for humans, they are important mainly as pests of several crops. Because of their occurrence in many habitats, they are often preyed upon by number of predators, including both vertebrates and invertebrates. However, Auchenorrhyncha implement various anti-predator defences to avoid it. This thesis summarizes available information about predation of Auchenorrhyncha and shortly deals with hunting behaviour of selected predators. In the second part, anti-predatory strategies and their occurrence in different Auchenorrhyncha groups are summarized. Furthermore, potential predators affected by those defences are discussed.
Acceptance of Fish Predators by Students of Chosen High Schools
Sůva, David ; Andreska, Jan (advisor) ; Hanel, Lubomír (referee)
The thesis describes the attitude students of professionally oriented high schools have toward chosen species of fish-hunting predators, namely the eurasian otter, the american mink, the great cormorant and the sea eagle. The first part of the thesis focuses on both historical and present recognition of these species in our country, description of each species including their population and protection measures. The second part of the text analyzes the curriculum framework of chosen high schools. The third part is a field study. The field study found which textbooks are used by students to learn about the fish-hunting predators listed above as well as the student's perception of them. A sample of 191 students were questioned, out of which 98 are students of schools of forestry and 93 are students of schools of fisheries. The worst acceptance was found with the great cormorant. The best acceptance was of the sea eagle. Key words: predation, eurasian otter, american mink, great cormorant, sea eagle
Bioacoustics in frogs
Karochová, Lucie ; Šandera, Martin (advisor) ; Schneiderová, Irena (referee)
This thesis is focused on bioacoustics in frogs. The purpose was to compare known informations about vocalization types, influence of sexual selection on males call, chorusing behavior and influence of predation. Bioacoustics research was carried on many frog species from different part of world, with most experiments being carried on neotropical frogs, specifically Physalaemus pustolosus. Acoustics communication is a wide-spread phenomenon across the animal kingdom. The theme of bioacoustics is studied quite extensively. The most studies is focused on birds or mammals, and the study of frogs, especially the European species, is poorly known. The influence of sexual selection on males vocalization is well known, while research in other evolutionary principles such as the effect of predator is studied only marginally. Research on new types of frogs tend to focus on the description of vocalization types that occur in a given species. In addition to in detail are studied individual voice parameters such as frequency or intensity and chorusing frogs are determined mainly by call-timing or synchronization. Newly was discovered ability of some frogs generate ultrasonic harmonies and surprising discovery was female vocalization as well. Generalization of facts is quite difficult because of the lack of...
The acoustic detection of potential predator in domestic horse (Equus caballus)
Vidimská, Tereza ; Komárková, Martina (advisor) ; Fuchs, Roman (referee)
Equidae belong to a group of large herbivores, which survival in natural environment depends beside others on their capability of fast predator recognition and detection. They can sensually recognise a possible threat in advance and react by immediate escape, which increases their survival. Also domestic horses still show very sensitive reaction to sudden (unexpected) stimuli. So we assume, that the ability to detect predator immediately is conserved despite of the long domestication process. The supportive indirect evidence is given by the successful breeding of the feral herds all over the world. However, studies showing the direct reaction of domestic horse toward the canids (as the most common predators), are still absent. Aim of the work was to find, if the horses (Equus caballus) could recognize acoustic sign of dogs like predators and if they could recognize the level of potential threat according to the number of predators, similarly as their wild ancestors. The recordings of barking of big dog breeds were obtained and modified. The final recording contained the set of barking coming from one individual or three different. The recording was played to the experimental horses, under controlled conditions, together with white sound as a control. The reactions were recorded. Altogether 12...
Surviving of Northern Lapwing (Vanellus vanellus) chicks in agriculture landscape
Kubelka, Vojtěch ; Šálek, Miroslav (advisor) ; Cepák, Jaroslav (referee)
The variability of egg-size within a bird species reflects different reproductive investments and, besides the intrinsic constraints and particular female quality, it can be affected by environmental factors, too. Moreover, the egg-size predetermines the chick performance. The knowledge of factors influencing precocial chick survival is crucial for better understanding of life-history strategies as well as for endangered species conservation. The Northern Lapwing (Vanellus vanellus) represents a suitable model species for investigation of climate variables effects on egg-size and also to study factors influencing chick survival. Eggs in a total of 714 nests were measured during 13 breeding seasons over period 1988-2014 in South Bohemia and 293 lapwing chicks from 100 broods in 37 localities were monitored in 2013-2014. The mean egg-size through the whole season is positively affected by March precipitation, March clutches also negatively by minus temperatures in March. The higher intensity of rainfall there is during March, the bigger eggs are laid in March and the steeper is slope of decline in mean egg-size during season. This decline is more profound with lower rainfall in April. The effect of habitat is not significant. The body mass and condition of hatchlings is positively correlated with the...
Diurnal vertical migrations of zooplankton in a stratified mountain reservoir
Adámek, Radek ; Hořická, Zuzana (advisor) ; Stuchlík, Evžen (referee)
The thesis - a literature review - was aimed at the phenomenon of diurnal vertical migration (DVM) of zooplankton, in relation to particular conditions in the Josefův Důl reservoir in the Jizera Mountains (northern Bohemia, Czech Republic). The area of the Jizera Mts has a very sensitive geology, and thus suffered a strong anthropogenic acidification in the second half of the 20th century. The consequence was a long-term degradation of chemistry and biology of soils and surface waters. The waters in the upper plateau of the mountains were fishless, with a low diversity and biomass of both the phytoplankton and zooplankton. Recovery from acidification is slowest in the deepest reservoir, Josefův Důl. Due to its morphology, thermal stratification, newly re-stocked brook charr population, and invertebrate predators' occurrence, the zooplankton distribution in the vertical profile is expected to be irregular, with DVM. The following diploma project, oriented to seasonal changes and vertical distribution of the zooplankton in the Josefův Důl reservoir, should contribute to long-term data on biological recovery of the reservoirs from acidification, and explain the role of biotic parameters in zooplankton succession.
Distribution and ecology of the turbellarian Dugesia tigrina in the Vltava river and selected Prague brooks and its interactions with native turbellarian species
Sevruková, Natálie ; Mourek, Jan (advisor) ; Hanel, Lubomír (referee)
Key words: (Dugesia tigrina), ecology, bioindication, predation, Vltava, Prague The main goal of my thesis was the research of occurrence and ecology of planarians of the group Ttricladida in the Vltava River and some brooks flowing through the territory of Prague. The emphasis was given on the non-native North American species - Dugesia tigrina. The research can be divided into field surveys of population size and ecological requirements of planarians and a laboratory experiment, in which I have investigated the predation behavior of planarians. During my fieldwork, which took place from August 22th to November 11th 2009, I have found out that the Dugesia tigrina occurs only in the Vltava river, in six of the nine studied localities. During the research it was not found in the studied brooks. It chooses localities with a natural shoreline, deeper ground, rapid water and it lives in company of mainly Dugesia polychroa. It appeared at moderately polluted places. During the predation experiment, which ran from December 17th 2009 to October 20th 2010 at a temperature of 14 řC and triple repetitions in all mutual combinations of five planarian species, intraspecific cannibalism and frequent asexual reproduction of Dugesia tigrina was comfirmed. The experiment showed mainly preying of indigenous...
Incubation behavior of the arctic tern Sterna paradisaea in extreme conditions of northern tundra
Hromádková, Tereza ; Pavel, Václav (advisor) ; Praus, Libor (referee)
Short breeding period and harsh climatic conditions are major limiting factors to which birds have to adapt in northern tundra regions. Despite this fact, dozen species of birds annually migrate into these regions to increase their chances to breed successfully. My diploma thesis focuses on incubation behaviour of the Arctic tern (Sterna paradisaea). The research for my thesis took place on the Norwegian archipelago Svalbard, in two particular locations: Adolfbukta and Longyearbyen. By using the method of continuous video recording, I described incubation behaviour of this specie in detail. Human activity is very different on each of Adolfbukta and Longyearbyen. On site Adolfbukta study was conducted during seasons 2012 and 2014, both with different predation pressure. Having known that, I could evaluate the impact of human activity as well as the impact of different predation pressure on incubation behaviour and breeding ecology of Arctic tern. The presence of human close to the colony had significant effect on incubation behaviour. Due to higher disturbances, incubating birds tended to leave their nests more often, attention paid to the nest was smaller and calm incubation (sleeping on the nest) was shorter by a half. Human activity had no effect on other displays such as average clutch size or...
The importance of water sources for space-use of mammals in African savannah
Homoláč, David ; Hořák, David (advisor) ; Brandlová, Karolína (referee)
African savannas are seasonal ecosystems experiencing a significant dry period each year. During the dry season, water scarcity has both, spatial and temporal consequences on the movements of large mammals. Some mammals can cope with these resource restrictions better than others. These water independent mammals predominantly feed on browse (giraffe, kudu, eland) and can be found further from water sources. However, these mammals can utilize areas near rivers as these areas provide food resources. Water dependent species are predominantly grazers and non-ruminants (zebra, wildebeest, elephant). Water shortage during a dry season restricts the movements of these species, which can be generally found in the vicinity of water bodies. Carnivore species (lions) react on the spatial restrictions of ungulates by adjusting their hunting areas to the vicinity of water sources. Both intra-guild (African wild dog) and inter-gild prey species (ungulates) develop anti-predatory strategies such as temporal and spatial segregation. African wild dogs use dens far from water points and ungulate species use to drink during daytime when lions are not active. Spatial and temporal segregation are also strategies to cope with competitors. Daily patterns of water point visitations can vary suggesting other factors...
Reasons and consequences of round goby (Neogobius melanostomus) invasion into the inland waters of Europe and North America
Starý, Vojtěch ; Čech, Martin (advisor) ; Vukićová, Jasna (referee)
Since the end of 1980s there is an ongoing massive invasion of fish from the family Gobiidae. The most widespread and aggressive of these fish is round goby (Neogobius melanostomus). Its natural habitat is area around Black and Caspian Seas, but nowadays it is already common in most of the European rivers, Baltic Sea and in the system of the North American Great Lakes. The main reason of the spreading is transport of ballast water from its natural habitat. The success of its invasion is due to the high tolerance to various factors like temperature, salinity, amount of oxygen in water, food sources and bottom substrates. Presence of the round goby in newly invaded rivers is beneficial for fish-eating predators. On the other hand competitors are highly disadvantaged as they lose in the fight with round goby over food, shelters and places for spawning and therefore, they are forced to live in less suitable habitats which leads to the decrease of their abundance. In recently colonized areas the round goby has much higher abundance than in its original habitats. The highest abundance is in the North America, where the round goby is causing the most noticeable change in the ecosystem. For this reason it is extensively studied mainly in the North America. Keywords: Gobiidae, Neogobius melanostomus,...

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